Objective: The objective of this study was to determine if clinical dynamic PET/CT imaging with C-L-methyl-methionine (C-MET) in healthy older women can provide an estimate of tissue-level post-absorptive and post-prandial skeletal muscle protein synthesis that is consistent with the more traditional method of calculating fractional synthesis rate (FSR) of muscle protein synthesis from skeletal muscle biopsies obtained during an infusion of L-[ring C] phenylalanine (C-Phe).
Methods: Healthy older women (73 ± 5 years) completed both dynamic PET/CT imaging with C-MET and a stable isotope infusion of C-Phe with biopsies to measure the skeletal muscle protein synthetic response to 25 g of a whey protein supplement. Graphical estimation of the Patlak coefficient K from analysis of the dynamic PET/CT images was employed as a measure of incorporation of 11 C-MET in the mid-thigh muscle bundle.